I need a program/utility to generate music from a computer file, for
the macintosh (OS8.6).

Ideally, I would be able to feed it a string of numbers representing
(e.g.) pitch, duration, volume, and it would generate an output file
in a easily readable format (e.g., mp3, aiff.)

A separate need is a program to generate a similar output, but with
pitch represented by the notes in the octave (e.g., I could feed it 'C
4 10', middle C, four seconds, volume 10.)

A *key* need is that I be able to feed it a file (and not, e.g., have
to do it by clicking or typing into the program itself.)

A bonus would be if I could mix this with other audio (e.g., "real"
music from an mp3.)

I would rather not learn MIDI, but if I have to, pointers would be
necessary for a primer.

The program(s) should be shareware or freeware.